Add doc string to methods

[TheRBen12]

Doc string and comments are still missing, they need to be added

"Steckenpfermethode" als gutes Beispiel neighbourhood_visualizer Z90 visualize_availability_when_price_is....( )

[Wii42]

Docstring conventions: https://peps.python.org/pep-0257/ How to specify return type / parameters: https://stackoverflow.com/questions/45004725/how-to-specify-different-return-types-in-python-docstring